Method of and apparatus for mining coal and the like



G. L. BENNETT Jan. 4, 938.

METHOD OF AND APPARATUS FOR MINING COAL AND THE LIKE Filed April 17, 1955 5 Sheets-Sheet l 'IIIIIIIIIIIIIIII ||||n.||||||l www G. l.. BENNETT 2,104,579

METHOD OF AND APPARATUS FIO-R MINING COAL AND THE LIKE Jan. 4, 1938.

Filed April 17, 1955 15 Sheets-Sheet 2 mlllllllllhllwa.

G. BENNETT 2,104,579

MINING COAL AND THE LIKE Jam 4, 1938.

METHOD OF AND APPARATUS FOR Filed April 17, 1955 s sheets-'sheet 5 INVENTOR 44 ATTORNEY Patented Jan. 4, 1938 UNITED srE METHOD OF AND APPARATUS FOR MINING COAL AND THE LIKE George L. Bennett, Terre Haute, Ind.

Application April 17, 1935, Serial No. 16,792

16 Claims. (Cl. 2672-4) The invention relates to a method of and apparatus for, mining coal and the like, and more particularly to a method which may be practiced without the use of explosives, and apparatus used in the practice of this method.

The invention will be described more particularly in its relation to coal mining which, notwithstandingl that modern practices and machinery have reduced materially the dangers inherent thereto, is still a hazardous occupation.

In the mining of coal, the practice usually iollowed is to remove the coal from the seams in the galleries or in the rooms leading therefrom by approximately defining the volume oi coal to be removed, undercutting and overcutting the seam adjacent the gallery or room oor and the top of the seam is resorted to, the undercut and overcut being approximately six inches in height, and in some instances being connected by vertical shears to reduce the wedging action of the coal upon its removal from the vein by a blasting operation. The holes for the explosive are then drilled, and the coal blasted from the seam by means of powder, dynamite or someother explosive. It is essential to remove the chain cutter from close proximity to the coal to be removed before the drilling operation, and to remove the drills before the blastingy operation.

The coal removed by the blast is loaded upon the mine cars by a loading machine, said cars being moved either by mules or by an electric locomotive. The labor item in mining coal by present methods is high, and the wastage of coal because of the shattering of the mass removed by blasting is great, since the under and over cutting and the shearing result in a high percentage of small particles of coal compared with the mass removed from the seam during cach blasting operation, and a considerable volume of small fragments results from the power exerted by the explosives. Furthermore, many of the larger pieces of coal are so shattered that they subsequently become disrupted by a contact with the outside atmosphere.

With the above conditions in mind, I have devised a method of mining coal and like material whereby the seam of coal is bored throughout a small area thereof to a desired depth and the bottom of this bore is counterbored or undercut to an extent to substantially define the width, height and thickness of the mass to be removed. After the boring and counterboring has been completed, the bore opening is sealed and a fluid under pressure is delivered to the counterboring, back reaming or undercutting, suilcient energy thus being exerted over a large area of coal to force the mass of coal outwardly of the seam.

' It is preferable, to avoid unnecessary and undesirable fracturing of the coal as a result of the high pressure active throughout a considerable area thereof, to dene the height `and width of the mass of coal to be removed by piercing the seam of coal at a plurality of closely adjacent points about, and spaced from, the bore opening, thus weakening the top, bottom and side edges of the block or mass of coal to'be removed. These piercings, however, are spaced from the counterbore, back reaming or undercutting sui'liciently to avoid dissipation through said piercings of the force developed by the fluid pressure when sepa- 15 rating the block or mass from the seam.

By this procedure, fracturing of the coal in the mass is reduced to a, minimum, and yet there will be sulcient breakage to permit the loading of the mine cars and the conveyance of the 0 mined coal from adjacent the seam in the usual manner. During the boring and counterboring, back reaming or undercutting in each block of coal to be removed, the chips may be conveyed from adjacent the opening being formed'as such chips are produced, thus avoiding interference with the drilling and boring operations. Such chips may be deposited upon the floor of the gallery or may be delivered directly to. conveyances, thus avoiding an accumulation of coal dust and small particles of coal about the apparatus being used. If delivered upon the oor of the gallery, they may be removed by shovel into the conveyances for removing them from the gallery.

In the practice of the method of the invention, I employ a special apparatus embodying therein a boring rod, the head of which has a center point and cutting tools upon the end thereof and radially expansible counterboring tools normally retracted within the bore head. The boring tool and the expansible counterboring tools are so actuated as to be simultaneously advanced through the body of the seam, the counterboring tols being capable of independent operation following the advancement of the bore tool to the desired point within the mass. In forming the counterbore, back reaming or undercut, the means for advancing the bore tool is made inoperative, and other mechanisms are thrown into gear to advance the expansible counterboring tools.

This apparatus embodies therein means whereby, concurrently with the boring of the mass in the manner above referred to, a plurality of drills defining thewidth and height oi" the block may be must be mobile to permit of suiiiciently rapid succeeding operations of the apparatus to make the actuated to pierce the coal or other material in the seam about the central Abore opening and spaced therefrom a desired distance to prevent the piercings made by the gangs of drills from entering the counterbore or undercut.

The boring tool and the various drill rods must be axially collapsible to permit the moving of the apparatus during the progress of the mining operation; and the apparatus itself, notwithstanding that it possesses considerable weight,

useA thereof economical. It must also embody therein means for holding it immobile during the drilling and boring operations, particularly as in the operation of the apparatus the aggregate pressure developed in the operation ofA and displacement of the apparatus as a whole Y will interfere with the operation of the appae ratus. Y. l

The invention consists in a method of mining coal and the like embodying therein the novel steps and practices, and in an apparatus for use in the practice ofy said method, all as hereinafter set forth and described and more particularly pointed out ingthe claims hereto appended.

Referring to the drawings,

Fig. 1 is a side elevation of; the boring and drilling endY of a machine;

Fig. 2 is a similar view of the opposite end of the machine; y

Fig.,3 is a detail view of the head and adjacent parts of the boring and counterboring mechanism;

Fig. 4 is a detail view of the sealing-off and pressure applying mechanism;

Fig. 5 is a rear view of the drill frame;

Fig. 6 is a longitudinal View, partly in section, of one of the drill rods and its actuating mech-V anism disclosing the manner of advancing same; and

Fig. '7 is an enlarged view showing the sep? arable cutting end 3l, attached to the supporting arm 30.

Like numerals refer to like parts throughout the several views.

' In practicing the method'of the invention, I

of a mass of coal or like material which is to be removed from a seam. The iloor and the ceiling. of the gallery define the limit of the vertical dimensions of this mass, and the depth of the mass is determined by the depth of the bore. When'boring has proceeded to the desired depth, I counterbore, back ream or undercut the mass of coal to substantially dene the Width of the mass to be removed. It is preferable, during the boring. operation, to deliver compressed air to the bore adjacent the boring head in a manner to force the chips and dust from the bore and from the undercut.

The central bore, after the completion of the boring and counterbo-ring operation, is utilized to deliver fluid under heavy pressure into the counterbore, the diameter of said counterbore being suiiiciently great to ensure a pressure area adequate to develop the force required to separate the mass from the seam as a result of the expansive force of the iiuid within the restricted space of the counterbore. When delivering the fluid to the chamber resulting from the counterbore, back reaming or undercutting it is necessary to sealoff or plug the bore at the face of the seam.

The above steps of boring, counterboring, sealing-off or plugging and applyingY expansible pressureto the back of the mass to be removed may be adequate when the coal or other material is sufciently soft to rupture readily, or, under certain conditions, where substantial regularity in the shape of the mass removed is not essential or desirable.V With harder material and Vunder other conditions, it may be desirable to limit the effective action of the expansible fluid, and to so weaken the top and sides of the mass to be `removed as'to ensure a limitation on the amount of material removed with each application of pressure.

When the above conditions are desirable, I dene .thel heightA and width of the mass of coal to be removed, by a. series of drill holes adja# cent the `floor and ceiling of the gallery and at the opposite sides of the mass. These drill holes are so located and of such a depth as to leave a sufficient barrier of coal or other material between the inner ends thereof and the counterbore, back ream or .undercut to preclude the escape of the compressed fluid through these drill openings. The weakening of the material of the seam by the removal ofV the material along Well dened lines, limits theresistance to the. separation of the mass of coal or other material to the strength of the material between these drill holes and the counterbore, back ream or unf dercut. Preferably, the drill holesv overlap to limit the dimensions of the Vconnectionsbetween the massto be removed, as Vdeiined by these opensealing-offer plugging theY center bore opening and delivering fluid under pressurel to the cham-4 ber formed back of the mass to be removed.

By the above procedure, a mass of coal weighing approximately six long tons may be removed with each application of fluid pressure, and this coal will be in sufficiently large pieces to avoid wastage from the shattering of the coal. Yet these pieces will not be sufficiently largeto preclude their proper loading in cars to be conveyed to breakers which` will reduce them to a desired size of coal.` In this manner, coal maybe removed inv a form whichv will give it the highest market value. n

By using suitable apparatus, the complete removal of the mass of coal above referred to may be accomplished in between two and three minutes. Such apparatus is shown in the accom-` panying drawings. Y f

The apparatus above referred tol consists of a carriage Il) having two sets of caterpillar tractor mechanisms II,Y and I2,those of one set II extending perpendicular to those of the other set I2. Each caterpillar track has its ownmotorV as I3 so as to impart the desired mobility to the said carriage. The caterpillars of one set II are provided with a lift mechanism shown at I4 so that when the apparatus is being used for boring and drilling, these caterpillars may be raised out of contact with the floor of the gallery and the caterpillars of the other set I2 allowed to rest upon said'roor. This will offer some resistance to movement of the carriage during the drilling and boring operation, although preferably itis not solely relie'd upon. When the cater-l pillars II are thus elevated, the carriage may be moved along the seam to permit successive boring and drilling of different portions of the seam.

Supported from said tractors is a hollow frame I5 supporting the boring and drilling mechanisms and inclosing same.

Upon the top of this frame is a pneumatic ings, and the seam from which this mass is to cylinder I6 having a piston |1, the head of which carries a plate having a plurality of spurs or studs I8. A valve controlled air line |9 communicates with the cylinder I6 so as to permit the elevation or lowering of the piston |1 to engage or disengage the spurs or studs I8 with the roof of the gallery, Throughout the machine fairly high fluid pressure is used so that with a large areaof piston |1, the chains or the treads of the tractors of the set I2 m-ay not only be forced under great pressure against the iioor of the gallery, but the spurs or studs I8 will be forced into the roof of the gallery in a manner to prevent any possible movement of the car- -riage during the boring and drilling operations.

The details of construction shown and above referred to are desirable in the apparatus, but it is obvious that any of the well known structures for imparting mobility to various kinds of different mechanisms may be employed, and that the cylinder I6 and its appurtenances could be dispensed with if sufficient weight were provided in the carriage structure. It is also obvious that other means of anchoring the carriage may be employed.

The carriage details above referred to are shown in Fig. 2 of the drawings and are embodied in one end of the apparatus.

Within the hollow frame |5 is a bore shaft 20, an exteriorly screw threaded bore shaft feed 2| loosely mounted upon said shaft toward one end thereof, a second exteriorly screw threaded counterbore feed 22 loosely mounted upon said bore shaft adjacent the forward end thereof, and a counterbore feed sleeve 23 non-rotatably mounted in relation to, but operative upon a rotary counterbore sleeve 24 carried by a bore head 25. The bore shaft 20 is connected directly with the bore head 25. Acting upon the bore shaft 20 through a gear train 26 is an electric motor 21, which during the boring operation, is continuously rotated at high speed.

The bore head 25 is providedwith a center spur 28 and cutting tools 29 upon the face thereof. Also carried by the bore head 25 are expansible cutting or counterboring tools 30, which during the operative moment of the cutting tools 29 are retracted within the bore head 25, but which may be projected from the head during the counterboring operation when the tools 29 are inoperative, for the purpose of producing by a counterboring operation, a chamber of a diameter commensurate with the volume of coal to be removed from a seam, but of a c-apacity to permit the development of the desired expansible force of fluid pressure to separate the mass of coal from the seam.

The counterbore tools or blades 30 may take a variety of different forms, it being required, however, that they shall possess sufficient iiexibility in at least one direction to permit their projection radially from the bore head, orv their withdrawal within said head.

In the drawings, these counterboring tools are shown as being of a laminated iiexible steel structure carrying a separable cutting end 3|, so that said end may be removed and replaced to permit the sharpening of the counterbore tool from time to time or the substitution of new for worn cutter ends upon said tools.

The bore shaft feed sleeve 2| is mounted in a fixed nut 32 and has rigidly mounted thereon, a gear 33 for imparting rotary movement to said feed sleeve. The gear 33 is driven from a pinion 34 carried by a sleeve 35 splined or otherwise slidably mounted upon a guide shaft 36, counter to the shaft 20. The shaft 36 is driven by the gear train 31 from a low horsepower reversible motor 38. Carried by the bore shaft 20 are three collars 39, 40 and 4|, the last of which is adjacent a forked plate 42 carried by the feed sleeve 2| adjacent the gear 33.

The application of power through the motor 21 to the bore shaft 2|] merely rotates said bore shaft and the head 25. The bore shaft 2|] is mounted in a bearing block 40 positioned between the collars 39 and 40 and connected by the mechanism 44 with the sleeve 35 so that this sleeve receives axi-al movement with the bore shaft 20. The mechanism 44 includes therein a shift lever 45 by means of which the sleeve 35` may be moved axially to disengage the pinion 34 from the gear 33 and thus interrupt forward movement of the bore shaft 20 and its head 25.

With rotation of the gear 33, the feed sleeve 2| acts upon, the collar 4| through the yoke plate 42 to impart lineal traverse to the bore shaft 20, while said bore shaft is being rotated. During this period, travel is imparted through the yoke member 42 and a channelled collar 46, to the feed sleeve 22 and the counterbore sleeve 23, there being, however, during this interval, no movement of said sleeve 23 in relation to the shaft 20. The sleeve 23 is held against rotation by gibs 41 carried by the shaft 23 and acting in guide grooves 48 upon said housing I5.

Also carried by the sleeve 35 is a pinion 49 adapted to be enmeshed with a gear 50 carried by the counterbore feed screw sleeve 22 so that when this sleeve 35 is shifted by the lever 45, thev gear 34 is moved out of mesh with the gear 33,` thus interrupting the forward movement of the counterbore shaft while it is still rotating andV the pinion 49 is enmeshed with the gear 59 to so turn the sleeve 22 as to impart lineal movement to the sleeve 23 for the purpose of projecting the counterbore cutters 39 from within the head.- This occurs while the bore shaft 20 is still rotating.

The hollow stem or sleeve 24 of the tool head 25 rotates with the bore shaft 20, and is connected withthe sleeve 23 by a joint permitting rotation of the sleeve 24 in relation to said sleeve 23.

A detailed description of the counterbore mechanism follows: j

The cutter blades 30 are rigidly mounted on a blade clamp member 5| slidably mounted upon the bore shaft 29 so as to be capable of movement toward and from the bore head 25. This clamp member is provided with feathers 52 entering a groove in the end of the shaft 23.

As stated above, the counterbore tools are preferably made of strips of flexible steel, two such tools being used. Said counterbore tools are positioned upon opposite sides of the longitudinal center of the bore head to provide necessary clearance for the movement of the tools during the counterboring operation. The strips of steel of which these boring tools are made are of sufficient width to impart thereto the desired rigidity in the direction of their angular movement. These tools are of a length to be projected beyond the head 25 to permit counterboring to the desired diameter, and the screw threads upon the sleeve 22 and the speed of rotation of said sleeve are such as to secure a gradual outward movement of the counterbore tools in proportion to the cutting speed possible with such tools. Of course, such speed is capable of considerable variation in adaptingfthe machine for work upon materials in which the resistance to the tools varies..

As heretofore state-d, it may be desirable in some mining operations to outline Ythe vmass of Y coal to be removed by a plurality of drill holes for the purpose of weakening the coalY or other material to an extent to limit the expansive force required to separate a mass of, coal from the seam, or to prevent excessive fracturing of the coal due to the development of such high pressure. f

With this in mind, I have provided a rectangular drill head 53 mounted upon the'housing I5 by means of supports 54. The frame ofthis housing is made in four'sections, a top section 5,5, a bottom section 55 and side sections 51 and 58. These side sections are provided respectively with interiorly screw threaded bosses 5S, co-operating with which is a lead screw 6%, theopposite ends of which haveV threads voppositely pitched. The top and bottom sections are connected'with the side sections 51 and 58 byy links 51,162, 63 andfl, so that when the side sections are dravvninwardly, the top and bottom sections will be move-d toward each other, these parts being slidably,v

mounted upon the supports 54.

Toward one end of the top, bottom and side members of the frame, cylinders 65' are formed, these cylinders being closely adjacent each other. Each of these cylindershas a piston 55 therein, the stem of each piston supporting a drill rod $31. i Each of the piston stems, toward theforward end thereof, in which end the drills 68 are mounted, is acted upon by a gear 69, a plurality of gears being enmeshed with each other, and different groupsoi gears being'simultaneously driven from independent motors. Each gear 69 is splined to a piston stem 61 so asto permit axial'rnovement of the piston stems and of the drills, as the drilling operation progresses.` The various piston stems or drill rods have an Aaxial opening therethrough, and each piston preferably has a'check valve 1I permitting air to pass from the cylinders through the rods for the purpose. of removing chips during thel drilling operation. The use of pneumatic pressure for advancing-the drills is desirable, in thatit permits a variable operation of the different drills to permit them to adjust themselves to varying resistances encountered during the drilling operation.Y YEach cylinder has an air supply pipe 12. f

The motors actuating the drills areshown at 13, 14, 15, 16, 1.1 and 18.

The particular-manner of applyingpower to the various drills is largely a matter of engineering design. Due to the large number of drills, however, and the movability of different sections ofthe main frame supporting the drills, a plurality of motors is necessary, thesemotors being movable with the frame part with which they are associated.

There is one lead screw l6! adjacent each pair of supports 54, and each of these lead screws carries a worm wheel 19 enmeshed with worm Wheels Y upon a shaft 80, which shaft 'carries a main gear Wheel 8| enmeshed withV a worm wheel 82 upon a handV operated shaft 83. By turning this shaft 83, it'is possible to partially collapse the drill frame when it is desired to move the apparatus as a Vwhole preparatory to succeeding boring and drilling operations.

As Will more fully appear hereinafter, after the boring, counterboring and drilling operations, when the latter is resorted to, the bore opening j is closed by'means of an exteriorly screw threaded plug 84. having well spaced threads which, by bitingxintov the material adjacent the end of the bore,.will prevent displacement of theplug. This mechanism it` is'V possible to delivercompressed airl tothe bore closely adjacent the counterbore and prevent any blow-out through the bore.

In the practice of the method of the invention, a hole is boredrby means vofthe cutting tools29, substantially centrally of a mass of coal or other mineral tobe removed. When this hole has been bored to the desired depth, the inner end of the holeis 'enlarged by counterboring, thus forming a shallow chamber of fairly large diameter Well within the seam.w If outline drilling is not to be resorted to, after the removal of the boring apparatus, the bore opening, at the face of the seam, issealedv or plugged and air or other fluid underheavy pressure is delivered through the Vseal or plug into the counterbore chamber, the a expansive power of this fluid forcing a mass of coal forwardly of the counterlooreV into the gallery or chamber. The expansive force of the fluid is sufciently great to break up the mass of coal thus forced from the seam, but without-undue fracturing of the larger particles thereof.

By outlining the mass to be removed by drillingr-in the manner above described, the force required to separate a mass of coal is less than Without such drilling, and consequently the degree of fracturing of the coal is much less than when the outline drilling is not resorted to.

The operation of the herein described apparatus is substantially as follows:

1 vThe tractors IVI are raised out of contact with the oor of a gallery, and the tractors I2 are used to move the apparatus sidewise along the gallery until the faceof 'the seamto be Worked uponis reached. The mechanisms I4 are then actuated to` force the tractorsl II into contact with the gallery floor and raise the Whole apparatus, in-

cluding' the tractors I2 to permit movement of the carriage toward the seam. The tractors II are then raised and air is admitted to the cylinder I6 driving the spurs or spuds I8 into the ceiling of the gallery, thus effecting the anchoring of the carriage in position. Before admitting air to the cylinder I6, the tractors II rare used to forcev the bore head into contact With the face of the seam.

Y When an outlinedrilling mechanism is used in the apparatus, the frame of this mechanism will be collapsedrduring this handling of Ythe apparatus, but after the apparatus has been positioned, the drill frame will be expanded so as to lbring the Ytop drills close to the ceiling of the gallery and the bottom drills close to the floor thereof. The drill frame, as to its forward edge, will be spaced somewhat from the face of the seam and a substantially airtight shield positioned between this frame and said face. Such a shield is shown at 93 in the drawings.

The various motors of the apparatus are then energized so as to have the boring and drilling occur at the same `time followed by counterboring.V yPower Yfrom the motor 21 is used solely to rotate the boring shaft 20. Power from the motor 38 is used successively to advance the drill rod 2i) and its head 25 as boring progresses; to actuate the feed sleeve 22 upon the completion of the boring operation and during counterboring, and to retract the bore shaft and counterboring tools. As the bore shaft is advanced through the action of the collar 4l adjacent the gear 33, the sleeve 23 will also be advanced by the yoke plate 42 and the feed sleeve 22 carrying the gear 50.

After the completion of the counterboring operation the motor 38 is reversed while the pinion 49 is still enmeshed with the gear 50, thus withdrawing the counterbore blades 30 within the bore head 25. When these blades have been fully withdrawn, and while the motor 38 is still operating in reverse, the sleeve 35 is shifted to enmesh the pinion 34 with the gear 33 and thus reverse the movement of the feed sleeve 2l so as to withdraw the bore head 25 from within the mass of coal or other mineral.

When the outlining drills are used during the boring operation, electric power from the various motors operative upon the numerous drill rods or piston stems will rotate these drills at high speed, air admitted to the cylinders 65 advancing the numerous drill rods so as to ensure a continuous drilling operation. If any drill meets greater resistance than other drills, the pressure in the cylinder will be maintained so as to advance that drill as rapidly as the drilling operation Will permit. Air passing through the drill rods will blow out chips and dust, the shield 93 z preventing the escape of this dust into the gallery or chamber.

After the completion of the drilling operations, sub-atmospheric pressure is developed in the various cylinders so as to withdraw the drills, the various cylinders being open at their forward ends for the admission of air to the cylinders for this purpose. Upon the completion of the boring and drilling, and after the various parts have been, as described, restored to their original position, the tractors l2 are used to move the apparatus a sucient distance to permit it to operate upon an adjoining section of the seam. When this operation has been repeated a number of times, the seal or plug 84 with the two tubes 85 and 88 is mounted in the bore opening, and air under pressure is introduced to the counterbore chamber to force a mass of coal or other material outwardly of the seam into the gallery or chamber as a result of the expansion of this air and the gradual development of suflcient force to break the material from the seam.

It is obvious that the use of outline drilling will greatly facilitate the separation of this mass of coal from a seam with less fracturing of the coal in the mass. Under some conditions, however, the drilling mechanism will make the handling of the device more diiicult and impart thereto a weight beyond what is desirable in the apparatus. Under such conditions, outline drilling need not be resorted to, and the drilling mechanism may be removed from the apparatus or may not be incorporated therein. Under such circumstances, boringand counterboring only may be resorted to, and this may be eiectively used to effect the removal of coal in lumps suliiciently large to permit the subsequent reduction of these lumps to desired commercial sizes by means of ordinary breakers. The amount of small sized coal and dust, even when boring and counterboring alone are relied upon, will be relatively small as com-v pared with the use of dynamite or blasting powders or other well known mining methods.

It is obvious that when there has been a succession of boring and counterboring operations before the separation of any coal from theseam the. volume of coal dened by each counterbore or by outline drilling, when such is used, may be readily removed without the loss of any substantial pressure because of adjacent counterboring, since the mass of material between counterboring will be sufficiently great to prevent the fracture of the coal along lines connecting such counterborings.

By means of an apparatus embodying the invention, coal may be removed very rapidly from a seam.

The time required to shift the apparatus along the face of the seam is not great, and, in the machine shown in the drawings, the boring and counterboring operations, andthe drilling operation When such is resorted to, are carried on at high speeds. It is estimated that the complete boring, drilling and shifting operation will occupy about three and one half minutes, so that with one man operating the apparatus and anotherv man operating the air pressure and plug mechanism, fifteen blocks of coal per hour may be separated from the seam. The tonnage per hour, of course, will vary with the size of the blocks removed.

The rapidity with which the work may be done permits the removal of coal from a seam more economically than with the use of explosive agencies, and the removal of such coal without the introduction of those hazards attendant upon the use of explosives. Furthermore, the quality of the coal mined by means of the method of the apparatus of the invention will be superior to that in which explosives are used during mining. The wastage of coal is also materially less than with the older methods.

The method of the invention involves the separation of coal in a mass, dened by a narrow counterbore chamber positioned well within the seam, by means of a progressively increasing expansive force, as distinguished from an explosive force. While breakage of the coal will occur as a mass thereof is being forced from a seam, the extent of this breakage is not comparable with that incidental to the mining of coal by explosives.

As fast as the boring and drilling is completed, air may be delivered to the counterbore chamber for pushing a mass of coal into the chamber or gallery, thus enabling a gang of two or three men to Work continuously in separating the coal from the seam, this separation being sufliciently rapid to ensure high economy. After the separation of the coal from the seam it is loaded in cars and removed from the mine in the usual manner, subsequent sizing of the coal being accomplished by machinery well known in coal mining.

It is not my intention to limit the invention to the precise details of construction shown in the accompanying drawings, it being apparent that the structure of the apparatus shown is subject to wide variation without departing from the spirit and scope of the invention.

The essential characteristic of themethod is the formation of a narrow counterbore chamber of fairly large diameter having a central bore leading in from the face of the seam and communicating with said chamber so as to permit the introducing of air under high pressure to said chamber, and utilization of the expansive force of the air to gradually separate a mass of the material being mined from. the seam.

' As stated, outlining drills may be used to better control the volume vof coal removed with each application of compressed air to a counterbore chamber, so as to minimize the expansive force required to separate a mass of coal from the seam, and at the same time permit the removal ofthe coal in larger pieces thanv when the exertion of greater force is required. y

Having described the invention, what I claim as new and desire to have protected by Letters Patent, is:-

1. The herein described method of mining coal and the like embodying therein the steps of boring a hole into a seam of the material to be'mined, forming a narrow counterbore at the end of said bore, said counterbore being of a diameter substantially equal toY the width and height of the mass of Vcoal to be removed, plugging the outer end of said bore, and deliveringfluid under pressure through said bore to said counterbore, whereby the expansive force of saidfiuid pressure will separate the material from the seam.

2. 'I'he herein described method of mining coal and the like embodying therein the. stepsofboring a hole into a seam of thematerial to be mined,

forming a narrow counterbore at the endof said bore, said counterbore being of a diameter substantially equal to the width and height ofthe mass of coal to be removed, plugging the outer end of said bore, and delivering compressed air through said bore to said counterbore, whereby theV expansive force of said compressedair will separate the material from the seam.

3. The 'herein described method of mining coalV n and the like embodying therein the steps ofboring a hole into a seam of the material to be mined, forming a narrow counterbore at the end of said bore, said count'erbore being of a diameter substantially equal to the width and height of the mass of coal to be removed, defining Vthe other two dimensions-of the mass of coal to be removed by a plurality of outlining drill holes, plugging. the outer end of said bore, anddelivering fluid under pressure through said bore to said counterbore, whereby the expansive force of said fluid pressure will separate the material from the seam.

Y 4. The herein described method of mining coal and the like embodying therein the steps of boringa hole into a seam of the material to be mined, forming ainarrow counterbore at the end of said bore, said. counterbore being of a diameter substantially equal to the width andY heightY of the mass of coal to be removed, defining the other two dimensions ofthe mass of coal to be removed by'a plurality of outlining drill holes, plugging the outer end of said bore, and delivering compressed air through said bore to said counterbore, whereby'the expansive force ofsaid compressed air will separate the material from the seam.

5. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted therein, means rotating said shaft, Va bore head carried by said shaft having. cutting toolsl on therend thereof,

means imparting feeding movement't'o said bore shaft during the boring operation, means whereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said'support axially of said bore. shaft, and a reversible power mechanism acting upon saidmeans imparting feeding. movement to said bore shaft, andsaid means'm'oving said counterbore support axially of said. bore shaft.

and expansible counterboring tools Y adapted to be projected radially of saidv head,

6. Apparatus for mining coal embodyingtherein a. mobile carriage, a bore shaft mounted therein, means rotating said shaft, a bore head carried by said shaft having cuttingtools on the' end thereof, and expansible counterboring tools adapted to be projected radially of said head, an

exteriorly screw threaded feed sleeve rotatably Vmounted upon said bore shaft, a xed nut enried thereby, an axially movable sleeve acted upon by said lastV named screw threaded. sleeve and operative upon said movable support, aV ro:- tatable counter shaft, a reversible power mecha.- nism actingv therefor upon said shaft, a sleeve slidably mounted upon said'counter shaft, pinions upon said sleeve, and means whereby said pinions may be selectively engaged withthe gears upon said screw threaded sleeves. ,l

' 7. Apparatus for mining coal embodyingtherein amoble carriage, a bore shaft mounted'there'- in, means rotating said shaft, aV bore head', carried byV saidshaft having cutting tools on the end thereof, said head having an axiallyfand radially extending f opening therethrough, a laminated counterboringtool, flexible in onel direction only; mounted in said opening,gmeans whereby said toolY m'ay have gradual longitudinal movement imparted thereto to project the cutting end thereof radially of said head,` means imparting feeding movement to said bore shaft. duringthe boring operation, means whereby the feeding movement of said shaft may be interrupted,v a movable support for'v said' counterborlngi. tool; meansy moving said support axially of saidv bore shaft, and aV reversible power mechanism acting upon said means imparting feeding mlovement` to said bore shaft, and said means moving saidl counterbore support axiallyofsaid bore shaft. f

8. Apparatus for mining coal embodying. therein a mobile carriage, a bore shaft mounted therein,.means rotating said shaft, a bore head carried bysaid shaft having cutting tools onthe end thereof, said'headhaving an axially and' radially extendingY opening therethrough, a laminated counterboring tool, flexible in onedirection only, mounted in'said opening,.means whereby. said tool may have gradual longitudinal movement imparted thereto to lproject the cuttingendthereof. radially of saidhead, an exteriorly screw threaded feed sleeve rotatably mounted upon said bore shaft, a gear carried by said sleeve, collars upon said bore shaft engageable bysaid sleeve, where'- by rotation of said sleeve will impartaxlalzmovement to said bore shaft during the boring opera.- tion, a movable support for said counterboring tool, a rotatableV exteriorly screw threaded sleeve upongsaidibore shaft, av gear carried thereby, an axially movable sleeve acted upon by said last; named screw'threaded sleeve and operative upon said movable support, arotatable counter shaft, a: reversible power mechanism acting upon said' counter shaft', a sleeve slidably mounted upon said counter shaft, pinions upon said sleeve, and means'. whereby said pinions may be selectively engaged with the gears upon said screw threaded.'

sleeves. v

9. Apparatus for miningcoal embodying'there.` in a mobilecarriage; abore'shaft mounted'there.-v`

inmeans rotating saidzgshaft, a bore g headfcarf` 753 ried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means whereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, anchoring means carried by said carriage, and means for actuating said anchoring means to engage same with the ceiling of a gallery or chamber to develop downward pressure upon said carriage.

10. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted therein, means rotating said shaft, a bore head carried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means whereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, a pneumatic cylinder at the top of said carriage, a piston within said cylinder, a plate carried by said piston having a plurality of upwardly directed spurs engageable with the ceiling of a gallery or chamber, and means whereby fluid pressure may be delivered to said cylinder to force said spurs outwardly of said cylinder and develop downward pressure upon said carriage.

11. Apparatus for mining coal embodying therein a mobile carriage, a plurality of right angularly arranged tractors supporting said carriage, means whereby some of said tractors may be vertically moved to permit movement of said carriage parallel with, or at right angles to, the face of a seam, a bore shaft mounted therein, means rotating said shaft, a bore head carried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means whereby the feeding mbvem-ent of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, and a reversible bore mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft.

12. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted therein, means rotating said shaft, a bore head carried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means whereby the feeding movement o-f said shaft may be in,- terrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, an outlining drill frame, a plurality of adjacent drills carried by said frame, means rotating said drills, means whereby said frame is mounted in relation to said bore shaft, and means simultaneously applying power to all of said drills to advance them during the drilling operation.

13. Apparatus for mining coal embodying therein a mobile carriage, a bore-shaft mounted therein, means rotating said'shaft, a bore head carried bysaid shaft having cutting too-ls on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement tosaid bore shaft during the boring operation, means whereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, an outlining drill frame supporting a plurality of adjacent cylinders, a piston in each cylinder, a drill rod carried by each piston, means whereby fluid pressure may be admitted to said cylinders to advance said drill rods during the drilling operation, means simultaneously rotating said drills, and means whereby said frame is mounted in relation to said bore shaft.

14. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted the-rein, means rotating said shaft, a bore head carried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially o-f said head, means imparting feeding movement'to said bore shaft during the boring operation, means whereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, an outlining drill frame supporting a plurality of adjacent cylinders, a piston in each cylinder, a drill rod carried by each piston, means whereby fluid pressure may be admitted to said cylinders to advance said drill rods during the drilling operation, means simultaneously rotating said drills, a valve controlled opening axially of each said piston and each said drill rod, the opposite ends of which open into said cylinders and outwardly of the drill rod adjacent the drills, whereby chips will be removed from the drill opening during the drilling operation, and means whereby said frame is mounted in relation to said bore shaft.

15. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted therein, means rotating said shaft, a bore head carried by said shaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means vwhereby the feeding movement of said shaft may be interrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon said means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, an outlining drill frame supporting a plurality of adjacent cylinders, a piston in each cylinder, a drill rod carried by each piston, means whereby fluid pressure may be admitted to said Y cylinders to advance saidrdrill rods during the drilling operation, means simultaneously rotating said drills, an opening axially of each said piston and each said drill rod, the opposite ends of which open into said cylinders and outwardly of the drill rod adjacent the drills, whereby chips will be removed from the drill opening during the drilling operation, a check valve controlling each said opening, whereby sub-atmospheric pressure may be developed in each cylinder to retract a drill, and means whereby said frame is mountedv in relation to said bore shaft.

16. Apparatus for mining coal embodying therein a mobile carriage, a bore shaft mounted therein, means rotatingY said shaft, a bore head carried by saidshaft having cutting tools on the end thereof, and expansible counterboring tools adapted to be projected radially of said head, means imparting feeding movement to said bore shaft during the boring operation, means whereby the feeding movement of .said shaft may be in-` terrupted, a movable support for said counterboring tools, means moving said support axially of said bore shaft, a reversible power mechanism acting upon saidY means imparting feeding movement to said bore shaft, and said means moving said counterbore support axially of said bore shaft, an outlining drill frame, said drill frame comprising a plurality of relatively movable sections, means whereby said sections may be actuated to collapseA said drill frame to permit some of said drills to be positioned adjacent the floor and adjacent the ceiling of a gallery or chamber or to be withdrawn toward the bore shaft to permit movement of the carriage, a plurality of adjacent drills carried by said frame, means rotatlng said drills, means whereby said frame is mounted in relation to said bore shaft, and means simultaneously applying -power'to all of said drills to advance them during the drilling operation. GEORGE L. BENNETT. 

